This invention relates in general to an improved electronic spelling machine and in particular to one having an enhanced ability to compare an input or query word against the set of words stored in the dictionary.
The utility of hand-held electronic spelling machines is essentially in their ability to provide an appropriate list of suggested matches against a query word and to do so in a minimum of time. This utility requires that the dictionary words selected for presentation to the user as a possible match against a query word be reasonably extensive, so that most likely correspondences will be presented to the user, and yet not so extensive as to overwhelm the user or make it unrealistic for the user to select the appropriate matching word.
It is also important to the utility of such a machine that the search procedure by which the query word is scanned through the dictionary be minimized to provide the user with a response that is as rapid as possible. The response time should be substantially less than the time that would be taken by the user to leaf through a dictionary in search of various possible matching words.
Accordingly, the major purpose of this invention is to increase the speed with which a query word is compared against the words in memory without excessively limiting the number of possible candidates provided to the user.
Applicant refers to U.S. Pat. No. 4,490,811 dated Dec. 25, 1984 entitled String Comparator Device System Circuit And Method and incorporates the disclosure of that patent herein. That patent discloses a string comparator technique of the sort with which the improvements of this invention operate. Accordingly, applicant will not disclose herein the particular string comparator techniques because such are disclosed in said '811 patent. In particular, applicant's references herein to word similarity characteristic is to the string comparison function .circle. disclosed in the '811 patent. For convenience, this function is called the theta function herein.
What applicant has done in connection with the embodiment of the invention described herein is to provide an enhanced technique for encoding strings of the type referred to in the '811 patent. Applicant has also provided an improved technique for limiting those portions of the dictionary in memory that are to be compared against a query word. This speeds up the process of traversing the memory which is in tree format. Applicant has also provided certain techniques for speeding up the decision making on whether or not to prune certain branches of the tree.